1. Field of the Invention
The present invention relates to material testing devices and apparatuses, and more particularly to an apparatus for determining the inter-fiber frictional coefficient of staple fibers.
2. Background Art
The study of parameters that contribute to the strength of yarn is one of the major areas of interest in the textile industry world over. One such parameter is the inter-fiber frictional coefficient of staple fibers, which are processed into a yarn. A frictional coefficient is a dimensionless scalar value which describes the ratio of the force of friction between two bodies and the force pressing them together. Staple fibers are categorized as visco-elastic materials, and the coefficient of friction between two visco-elastic materials ranges between the values 0.66 and 1.
It has been scientifically established that: at low levels of inter-fiber frictional force, the yarn strength is equivalent to the inter-fiber frictional force, at moderate levels of inter-fiber frictional force, the yarn strength depends on the tensile strength of the fibers and the inter-fiber frictional force, and at high levels of inter-fiber frictional force, the tensile strength of the fibers is equivalent to the yarn strength. Based on this principle, since, as mentioned before, the inter-fiber frictional coefficient is low for visco-elastic materials, it could be stated that the maximum frictional force exerted by staple fibers in a sliver is equal to the tensile force or strength thereof.